a) Field of the Invention
The present invention is directed to a compact spectrometer in which the electrical and optical components are permanently connected to one another. A minimal expenditure on assembly and adjustment is achieved through a small quantity of individual parts.
b) Description of the Related Art
According to the known prior art, miniaturized spectrometer systems are often needed so as to ensure a broad range of application. The combination of high-performance digital electronics with the optical components and the use of flexible light-conducting fibers results in spectrometers whose areas of application range from routine analysis in the laboratory to special tasks in process measurement technology and quality control in manufacturing processes. Consequently, numerous spectrometric systems for many different applications are known from the art.
An arrangement for measuring optical spectra is described in DE 198 36 595. In these spectrometers, the optical and electronic components are arranged one above the other in a sandwich-type construction and are permanently connected to one another, Owing to this manner of construction, these spectrometers are very compact and robust. However, the expenditure on adjustment of the optical components, particularly reflection gratings and mirrors, appears to be considerable.
The spectrometer described in EP 1 041 372 has means for connecting the individual optical components in a simpler manner in order to reduce expenditure on adjustment of the optical system, which is an important cost factor in the manufacture of spectrometers of this type.
Concentric spectrometers are described in U.S. Pat. No. 6,181,418 and U.S. Pat. No. 5,995,221. Due to the concentric shape of the housing parts and other structural component parts, thermally-dependent expansion and stress can be kept well under control. The proposed solution reduces stray light and reflection spectra which substantially influence the sensitivity and measurement accuracy of the spectrometers. In this solution, expenditure on adjustment is also considerable due to the large number of individual parts.
In the solution described in DE 196 09 916, a miniaturized compact spectrometer is used for the detection and sorting of plastics in the recycling industry. For cost reasons, instead of complete lines of detectors, a small number of irregularly spaced detectors are arranged at the points of the generated spectrum that are sufficient for detecting and distinguishing sorts of materials. While this reduces the readout time and evaluating time, the expenditure on adjustment and assembly is increased due to the individual detectors.
Utility Model Application DE 299 06 678 describes a small spectrometer for determining the condition of surfaces of roadways and/or vehicles. The housing parts are manufactured in such a way that they have cutouts, grooves and pins, so that the other structural components parts can be brought into the pre-defined position in a simple manner. Accordingly, only a slight expenditure is required for fine adjustment.
However, the spectrometer arrangements mentioned above have the disadvantage that, even with optimized manufacture requiring only a fine adjustment of the optical components, the expenditure on assembly and adjustment is too high due to the quantity of elements to be adjusted. Accordingly, economical and effective large-scale production is impossible.